Loading tray



June 7, 1949. c. E. ELLSWORTH LOADING TRAY 2 Sheets-Sheet 1 Filed April 22, 1946 INVEN TOR 54 41. f fZLJu O/PTH ATTORNEYS June 7, 1949. c. E. ELLSWORTH LOADING TRAY Filed ApriI 22, 1946 2 She'ets-Sheet 2 ATTORNEYS Patented June 7, 1949 UNITED ESTATE-s PATENT omen "Carl E. Ellsworth, Louisville, K;y., as"signor to lhe 'Girdlerpdrporation, Lou'is'ville, Ky., a corporatidn of Delaware Application April 22, 1946, Serial No. 664;028

(c1. "rs- 1") '10 "Claims.

1 invfitibh relates t0 the dielectric heating 6: .efiiects'in a'hig'hfr'e'quenc'y heating unit and liiitfclilarly ito 'the Construction of .a loading tray "therefor "which provides for simultaneous disfiibff'e "off 'heate'd objec ts en's, in reloading of the tiefy, ffadilita'tes l'p'le'eem'ent and maintenance of "flie-b'bfctswih proper spaced relation.

faidcoiiiance with tiny invention, -'the tray, wflifch ipi''i'rably serves as one of the heating electrh'de's, v comprises relatively movable parallel plate -In'ii'Trie'r's each having holes 'therethrough which may be moved into and out of alignment with the corresponding holes in the adjacent piste. "Thep'l'ates when their o enings are out n: filik fiini'it, "provide -.a, support having shallow iiiscfis'ss to receive the 'ob'jectsto beh'eated. After heo'tihg 6f the objects "and removal of the tray fl-bin the unit, the plates are relatively moved to firingthe"cerrespdndingopenin s into alignment,

'sotj'liiliiiitting the objects to .pass through the tiiiy, More specifically, the tray comprises 'top snt'tettdm plates which are stiffened andjoine'd nyigrooved members extending between adjacent sews et alignediopenings in the plates and-servfo'r a'lgroup of interconnected plate sfiiubtuies, each having openings which may be moved fi'fito and nut er alignment with the correopen'ings in "the top and bottom plates.

fltlfyflnventlonfurthe'r resides in features of eonstreet! and'dlitiin'ed. 'Fo'rfamore'd'tailed understanding at int inve'r 1tion end for illustration er a prererrea i'dfmthereof, "reference is made to the accant-partying drawings, in which l, "in perspective, shows a high-frequency :1

unit with the loading tray empty and peiftihl'ly'withdrawh "from theunit;

*Fi 2 eiegrtnnmettican illustrates the relation dl "the tented tray to elements 'of the high frequency unit;

jFig. 3 is a. plan View, parts broken away, 61 the lending trayshown in Fig. 1;

4 is e, 'tiete'n view, in perspective and on enlarged scale, showing net-ens of internal constrpction of theloading tray;

me. *5 is a detail 'iii'ew o'n enlarged scale showrug plate interconnecting 'ine'ans and e tray runes e,

1511s a; e'etan view in section taken on line itere'rnng to Fig. 1, the heating unit I is of a teen to pr sent, 'f'o'i' example, les'ti 'preentrants to be molded in e press to term 'f'azticles as distributor needs for internal eesltwstrdn 'ens'in'es. preterm s received.

Oh and arrangement hereinafter described in 'the press should be evenly heated to proper molding temperature; if they are insufiieiently heated great pressure -is-required to shape them and there {is danger of breaking, deforming, or displacing from proper position metallic inserts i'n'old'ed into the preforms during their shaping in the press. 1f, on the otherhand, the temperature is toog great, the preforms prematurely begin to set, if they are of thermosetting plastic matene with mu'ch t he same disastrous results.

=A thermosettin'g material often used for such preforins is -mine'r-al-fil-led melamine resin of whi dhit'is characteristic that there is but slight difference between the softening point, the flow point, en'a ;the setting-up point. It is, therefore, necessary that after the preforms have been heated they be transferred as quicklyas possible to the moldingpre'ss.

Furthermore, the preforms when heated to the proper t mperature are of consistency similar to that of putty and should, therefore, be subjected to a minimum of handling.

his will hereinafter appear, the construction of the loading tray 2 is such that after a batch of pre enns F, 2, have been heated and the tray ttnth'erewn item the heating unit, all the preform's maybe simultaneously released in proper on 'in a multiple press merely by pulling the 'd'l' l' osiite sides of the trey and then lifting itto clear the dishar ged batch.

As shown in Fig, 3, the tray {is formed by an upper-plate 3 and a lower plate 4 having a series of rows-er openings '5 afid'B res'peetively, each hole 5 in the topplate being in alignment with a corresponding he1es-inthe bottom plate. The diamet'r of the holes 5 and P6 'is sufiiciently large to neethe particular 'pre'form's 'for which the tray 'is to he used. The plates 3 and 4 are prefrabl ythin sheets of aluminum or other suitable metal which are stiffened and joined 10y a series of reinforcing members I, each extending crosswise of the sheets inthe space between them and substenti-euy midway between the adjacent rows of hbl's in "the plates Each of the reinforcing member '1 may be int nsity of H cross-section errne netenneeted min, for example, a rectanu'la'r bar 8, Fig '5, "to the upper and lower sides fo'f are respectively attached the strips 9 en To. The eer e a ens the strips '9 and In Chief? be held ii'l position to'fn'rm an 'H-beain, Figs. 4 and 5, By screws Tl wnidnpess through the iiiip rlri d lowerpl'ates 3 and 4 and through the fi iiistlil sfi and l ll'threali ably to h- 'ga ge 'the web-Io re-reanee the f ional "fesisttin):ehetween the loading tray and its supporting structure in the heating unit l during its insertion into, and withdrawal from, the heating unit, two or more runners or straps it! may be attached to the under side of the tray. For example, as shown in Fig. 5, a runner 36 extending crosswise of the bottom plate may be disposed opposite a reinforcing strip ID for attachment by the same series of screws ll used to hold the bottom sheet l against the strip [0, The ends of the tray may be closed, Fig. 3, by the angle pieces ii, iii which also serve as runners. Each of the pieces 92 is secured to the under face of the bottom plate 3, as by screws which pass through the angle piece and the plate, threadably to engage the corresponding end-reinforcing bar It. lhe top plate 3 is also secured to the reinforcing bars l 75 by screws ii i.

The front of the tray 2 is closed by the angle piece l4 secured to the under face of the bottom plate 4, as by screws 32 which pass through the angle piece, and the plate, threadably to engage the web-forming bars 8, Fig. 6. To this side of the tray, and preferably to the closure member l4, there are attached the metal handles it which are accessible to the operator for withdrawing the tray 2 and its load from the heating unit I.

Beneath each series of openings 5 in the upper plate 3, there is slidable an elongated plate structure I9, preferably of sheet aluminum, in length substantially correspondinng to the width of the tray and having therein a series of openings 29 so located that when the plate structure I9 is pulled partially out of the tray to the position shown in Fig. 4, the Openings 5, 2s and 6 are all in vertical alignment to permit the heated objects or preforms to slip through the tray. Betraction of the plate structure iii beyond the position shown in Fig. 4 is precluded by engagement between the pairs of stop members and 2|, respectively attached to the movable plate structure l9 and to the main body of the tray formed by the plates 3, l, and their interconnecting members I. In the particular arrangement shown, each of the stop members 2i] is secured to one end of a rod 22 which. at its other end, is attached to the member 23, itself interconnecting through screws 55 the several plate structures l9 so as to provide for their movement in unison toward and from the loading and unloading positions.

As clearly appears in Fig. l, each of the plate structures l9 has a central raised portion which preferably only slightly clears the under face of the top sheet 3 so that essentially the entire mass of a preform, received in a shallow recess provided by an opening 5 and resting upon the plate structure [9 directly below it, is above the plane of the top plate. The plate structure is is bent downwardly outwardly in opposite directions from the raised central portion to stiffen. the plate structure longitudinally and to provide for attachment of the opposite edges of the plate, as by pinning, to the slotted stiffening and guiding bars 24, which are slidably received in the guiding grooves between the flanges of the H-members i. To the rear slide member 23 which interconnects all of the plate structures l9 are attached the handles 25 which, together with the handles it fastened to the main body of the tray, provide a means for both lifting and carrying the tray, loaded or unloaded, to or from the dielectric heating unit I. By pulling on both of the handles 25 and 16, Fig. 3, which is possible only when the tray 2 is out of the heating unit, all of the plates l9 are retracted, Fig. l, for unloading of the tray. By pushing on the handles 25 and Hi, all of the plates l9 are reinserted, Fig. 3, for support of another batch of preforms or other objects to be heated. When tray 2 is in the heating unit I, the rear handles 25 of the tray are not accessible and they remain so until the tray is withdrawn, thus precluding accidental displacement of the preforms.

The main members of the tray are preferably of aluminum for lightness and good electrical conductivity. All members, including 38], 24, 8, 9, l0 and I2, which are subjected to sliding friction are of brass, copper-plated steel, or other material suited to withstand wear.

As shown in the simplified circuit diagram, Fig. 2, the power supply circuit of the high-frequency generator 21 of unit I includes the tray switch contacts 26 in series with a switch 28 used to start and stop operation of the generator. Unless the tray is in proper position, with the contacting member ll on the rear edge thereof eifecting closure of switch contacts 26, the highfrequency generator cannot be operated. The tray 2 must be inserted with the movable handles 25 leading the tray. The stationary or framesecured handles it are positioned for withdrawal of the tray 2 from unit i. Thus, the required force for insertion or withdrawal of the tray may be exerted without danger of discharging or dumping preforms with the tray in place in the unit I.

The shallow recesses in the tray facilitate spacing of the objects between the electrodes 2 and I8 and reduce the chances of accidental displacement of the objects in normal handling of the tray in loading and unloading of the unit I and in loading a multiple-plunger press. They also insure that the preforms, as delivered in the tray to the press, are all in proper position so that merely by pulling the tray handles, all are at once discharged in readiness for the press operation. The rapidity with which all heated objects of a batch may be transferred by this tray from the heating unit to the press greatly minimizes the possibility of overheating of some, or all preforms in effort to allow for longer time, of transfer or of undesirable low temperature of at least some preforms because of excessive time lost in their transfer to the press. In addition, use of the tray results in reduced labor costs.

The tray being of metal having good electrical conductivity is not heated by its disposition in the electric field which heats the preforms or equivalent and may, therefore, be safely, easily and manually handled. The operator in withdrawing or reinserting the tray 2 is in no danger of electrical shock or high-frequency burn because although the tray is one of the electrodes, it is at ground potential.

It shall be understood the invention is not limited to the preferred embodiment shown but is subject to changes and modifications within the scope of the appended claims.

What I claim is:

1. A loading-tray electrode for a high-frequency heating unit comprising metal top and bottom plates having rows of aligned openings therethrough, members each between adjacent rows of said openings for joining said plates in spaced relation, a plurality of plate structures each slidable between said plates with its edges plates for unloading and loading of the tray, and

@- imemhercnnectin the. ends of sa d te stru tures to effect their mo ement in unis n to and from loadin and un o n pos tions- A loading-tray electrode for a high-frequency heating unit comprising thin metal top and bottom plates having rows of aligned openings therethrough, grooved reinforcing members jo ng said plates between adjacent rows of said openin fi, a plurality of metal plate structures each slidable between said plates with its edges received by the grooves of an adjacent pair of said reinforcing members and having openings movable into and out of alignment with the openings in, said plates for unloading and loading of the tray, and a member interconnecting the ends of said plate structures to provide for their movement in unison to and from loading and unloading positions.

. .3. A, loading-tray electrode for a high-freduency heating unit comprising thin metal top and bottom plates having rows of aligned openings therethrough, grooved reinforcing members joining said plates between adjacent rows of openings, a plurality of metal plate structures each slidable between said plates and having a row of openings movable into and out of alignment-with the o enings of the correspondin rows in said plates for unloading and loading, pairs of stiffening and guiding bars, each pair stiffening the opposite edges of one of said plate structures and received by the grooves of an adjacent pair of said reinforcing members, and a member interconnecting the ends of said plate structures to provide for their movement in unison to and from loading and unloading positions.

4. A loading-tray electrode for a high-frequency heating unit comprising thin metal top and bottom plates having rows of aligned openings therethrough, reinforcing members each be tween adjacent rows of said openings for maintaining said plates in spaced relation, runners extending along the under surface of said bottom plate, fastening means for said runners each passing through said bottom plate and into one of said reinforcing members, a plurality of plate structures each slidable between said plates and guided by an adjacent pair of said members and having openings movable into and out of alignment with a row of said aligned openings in the top and bottom plates for loading and unloading of the tray, and a member connecting the ends of said plate structures to effect their movement in unison to and from loading and unloading positions.

5. A loading-tray electrode for a high-frequency heating unit comprising spaced rectangular top and bottom plates having rows of aligned openings therethrough, means for closing the front and side edges of the tray and interconnecting said plates, reinforcing members extending from front to rear of the tray each between adjacent rows of said openings and attached to said plates, a plurality of plate structures each slidable between said plates, guided by an adjacent pair of said members, and having openings movable into and out of alignment with the corresponding row of said aligned openings for unloading and loading of the tray, and a member interconnecting the movable plate structures at the rear of the tray to efiect their movement in unison to and from loading and unloading positions and to close the rear edge of the tray when they are in loading position.

6. A loading-tray electrode for a high-frequency heating unit comprising spaced rectangular top and bottom plates having rows of aligned openings therethrough, means including angle pieces which close the front and side edges of the tray for holding said plates in spaced relation, grooved reinforcing members extending from front to rear of the tray each attached to said plates between adjacent rows of said openings,'a plurality of intermediate plate structures each with its sides slidably guided by an adjacent pair of said grooved members and having a row of openings movable into and out of alignment with the corresponding row in the top and bottom plates, and a member movable to close the rear edge of the tray and there interconnecting said plate structures to effect their movement in unison to and from loading and unloading positicn 7. A loading tray comprising top and bottom plates having rows of aligned openings therethrough, grooved reinforcing members each between adjacent rows of said openings for joining said plates in spaced relation, a plurality of intermediate plate structures each having a row of openings movable into and out of alignment with a row of said aligned openings and each bent downwardly and outwardly along opposite edges, pairs of stiffening and guiding bars, each pair stiffening said opposite edges of one of said plate structures and received by the grooves of an adjacent pair of said reinforcing members, and a member interconnecting the corresponding ends of said plate structures to provide for their movement in unison toward and from loading and unloading positions.

8. A loading-tray electrode for a high-frequency heating unit comprising top and bottom plates of metal having light weight and high electrical conductivity having rows of aligned openings therethrough, grooved reinforcing members each between adjacent rows of said openings for joining said plates in spaced relation and each of metal having high rigidity and good surface wearing quality, a plurality of plate structures each slidable between said plates and having a row of openings movable into alignment with a corresponding row of openings in the plates, said plate structures each being of light-weight metal, pairs of stiffening and guiding bars, each pair stiffening the opposite edges of one of said plate structures and received by the grooves of an adjacent pair of said reinforcing members, said bars each being of metal having high rigidity and good surface wearing quality, and a member interconnecting the ends of said plate structures to provide for their movement in unison to and from loading and unloading positions, said last-named member being of metal having high rigidity.

9. For use with a high-frequency heating unit, a portable loading tray electrode removable therefrom for loading and unloading of dielectric objects to be heated and comprising an upper plate having openings therethrough to receive and space said objects, a lower plate slidable with respect to said upper plate and having openings therethrough, which when aligned with the openings of the upper plate provide for discharge ofsaid objects, said lower plate frictionally engaging said unit during insertion into and withdrawal of the tray from said unit and being slightly spaced from said upper plate to provide, upon misalignment of the openings of said plates, shal- 10w recesses precluding accidental displacement of said objects in handling of the tray, and handle means connected respectively to the front end of said lower plate and to the rear end of said upper plate for accessibility of only one of them when the tray is in said unit in avoidance of accidental displacement of said objects and for accessibility of both of them when the tray is out of said unit for handling of the tray and for efiecting relative sliding movements of said plates in loading and unloading of the tray.

10. For use with a high-frequency heating unit, a portable loading tray electrode removable therefrom for loading and unloading of dielectric objects to be heated and comprising an upper plate having openings therethrough to receive and space said objects, a lower plate slidable with respect to said upper plate and having openings therethrough, which when aligned with the openings of the upper plate provide for discharge of said objects, said lower plate frictionally engaging said unit during insertion into and withdrawal of the tray from said unit and being slightly spaced from said upper plate to provide, upon misalignment of the openings of said plates, shallow recesses precluding accidental displacement of said objects in handling of the tray, handle means connected respectively to the front end of said lower plate and to the rear end of said upper plate for accessibility of only one of them when the tray is in said unit in avoidance of accidental displacement of said objects and for accessibility of both of them when the tray is out of said unit for handling of the tray and for effecting relative sliding movements of said plates in loading and unloading of the tray, and a switch member mechanically connected to said upper plate for permitting operation of said heating unit only when said tray is so inserted therein that the handle connected to the lower plate is accessible externally of said unit.

CARL E. ELLSWORTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 767,872 Davies Aug. 16, 1904 1,742,670 Schmidt Jan. 7, 1930 2,365,849 Strauss Dec. 26, 1944 OTHER REFERENCES Rahm: Plastic Molding, published in 1933 by the'McGraw-Hill Book Co. of N. Y., pages 196 and 197. Copy in Div. 15.

Thermis, a circular published by the Girdler Corp. of Louisville, Ky, Aug. 21, 1944. Copy in Div. 15, Elec. Heat Dig. 

